Modbus Communication Port Register Map; Viewing/Setting Modbus Parameters; Communication Protocol; Modbus Register Map - Eaton Power Xpert Release PXR 10 Manual

9 Available protection settings

10 Modbus communication port register map

A ModbusRTU communication module is integrated to the trip unit for certain styles.

10.1 Viewing/setting Modbus parameters

Modbus connection parameters can be viewed and set from LCD display, via PXPM and
Modbus communication. To view from Modbus communication, the settings are stored
beginning at register number 404000 and extending through 404003 and may be read by
using function code 03 or 04, listed in the following table. These four registers can be
written one by one with function code 06 to change Modbus setting. If the data written into
these registers is out of range, it will result in an exception code 03.
Definition modbus register number
Slave ID 404000
Baud rate 404001
Parity 404002
Stop bit 404003

10.2 Communication protocol

Only the Modbus RTU communication mode is recognized by the trip unit. The trip unit can
support a maximum of 122 registers (244 data bytes) in a single Modbus transaction. The
trip unit responds to Modbus function codes 02, 03, 04, 06, 08 and 16.

10.3 Modbus register map

10.3.1 Input status (discrete inputs)
Input status bits 101001 through 101032 may be available using function code 02. The status
definitions are defined the following table. The first 16 bits are the actual status state while
the late 16 bits indicate whether the corresponding status state is valid, or supported by the
trip unit.
input Definition
1001 Breaker is in the closed position
1002 Un-acknowledged trip condition
1003 Active or un-acknowledged alarm
1005 Maintenance mode is active
1006 Test mode is active
1010 Long delay pickup is active
1011 Zone interlock is active
1013 "Ground" is source ground
10.3.2 Real-time data object registers
The data changing in real time, such as current, voltage, power, etc. are shown in the table
below. Real time data can be obtained either in IEEE floating point or in fixed point format.
For data shown in fixed point format, each result would be the real time data multiplied by
a scale factor. The scale factors are shown as the last column in the table. Energy objects
can be only obtained in fixed point format.
Each data object occupies two registers (four bytes) in length except for certain energy
objects. These energy objects occupy four registers. Since these objects have the capability
to change in real time, a complete data object must be obtained in a single transaction to
avoid data tearing. Attempting to access a partial data object will result in an exception code
84. Refer to a later section entitled "Exception codes" .
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Data range
001 – 246 (factory default = 2)
00 = 9600 bit/s
01 = 19200 bit/s (factory default) 02 = 38400 bit/s
03 = 57600 bit/s
00 = None
01 = Odd
02 = Even (factory default)
00 = 1 bit (factory default)
01 = 2 bits
input Definition
1017 Breaker is in the closed position is valid
1018 Un-acknowledged trip condition is valid
1019 Active or un-acknowledged alarm is valid
1021 Maintenance mode is active is valid
1022 Test mode is active is valid
1026 Long delay pickup is active is valid
1027 Zone interlock is active is valid
1029 "Ground" is source ground is valid